Wolf Tooth Knock Block Premium headset upper 1 1/8' IS41/28.6/H8

Wolf Tooth Premium Headsets for Trek Knock Block are machined in the USA out of aircraft-grade 6061 aluminum with superior sealing for protection against the elements. Available in a variety of colors to match the style of your bike. These upper headsets are for Trek frames with molded-in internal bearing cups.
Trek developed Knock Block as an integrated frame protection system to prevent self-inflicted scuffs, dents, or cracks from spinning handlebars. Knock Block consists of a special stem and stop chip on the frame. The stop chip limits the turning range of the custom keyed headset cover. The top of the headset cover has notches that lock into corresponding notches on the headset spacers which also correspond with notches in the stem for the strongest connection to the steer tube. These parts work together to prevent the crown of the fork and the handlebar controls from hitting the frame.

• Compatibility: Designed to work only with Trek Knock Block system
• The top cap on these headsets have unique raised features that key to Knock Block-compatible stems (made by Bontrager)
• If spacers are needed, you will need to use special Knock Block-compatible spacers with notch features
• Weight: 52g
• Stack Height: 7mm
• Material: 6061 aluminum
• Stem Cap Bolt Torque Spec: 2-3 Nm with light grease on threads only
• Made in the USA